A variety of processes are generated by-products that are harmful or otherwise undesirable. For example, the production of electricity by coal fired production plants creates by-product materials containing toxic waste. As coal is burned, toxic heavy metals such as Mercury, Arsenic, Cadmium, Lead and other substances become gases. Molecules of these gases cool in exhaust systems and collect with fine ash particles to make fly ash. Heavy ashes fall during coal combustion to create bottom ash. These materials are often stored in piles or in ponds at production facilities. The presence of these sites creates a potential hazard to human populations, at least in part due to the ability of toxins to dissolve in water supplies. Once in water supplies, the toxins can become a threat.
As another example, slag piles and other by-products of industrial processes such as mining, metal smelting and refining can pose potential problems. For instance, toxic lead, arsenic, copper, selenium and other contamination may be generated from such processes. These and other matters have presented challenges to managing by-products of a variety of applications.